The present invention relates to wireless communication methods and wireless communication apparatus, particularly to those utilizing the SDMA (Space Division Multiple Access).
Various multiple access schemes have heretofore been known for realizing the multi-user access in the wireless communications. The SDMA is one of the multiple access schemes aiming at improvements on the spectral efficiency, in which use is made of a plurality of antennas for establishing spatially divided or separated propagation paths for simultaneous multiple access using the same frequency. In recent years, owing to the development of the MIMO (Multiple-Input Multiple-Output) wireless communication schemes, technologies have been laid open in which space division multiplex wireless communication technologies utilizing the MIMO have been extended to implement the multiple user access. FIG. 1 is a schematic diagram of a wireless communication system utilizing the SDMA. In this drawing, it is illustrated that communications are achieved between an access point (AP) 101 and u user terminals (UT's) 102-1 to 102-u, implementing the SDMA. An example of the implementation of the SDMA is described in U.S. Patent Publication No. 2004/0252632A1, which is incorporated by reference.